1. Field of Invention
The present invention relates to chiller systems. More particularly, the present invention relates to a method for optimizing a chiller system by evaluating performance of the chiller system, which is capable of evaluating power consumption of a chiller system through a number of activated chillers, a number of activated cooling towers, and a lowest outlet temperature of cooling water of cooling towers of the system.
2. Related Art
As for places those require air conditioning control, for example, air conditioned buildings, semiconductor factories, and cold storage warehouses, chiller systems are required to provide chilled water to chill the a in those place. Large amounts of electrical power are used by chillers of an air condition control system, and thus, how to improve the efficiency of the chillers becomes an important power-saving issue for being researched.
For the factories or buildings being built, the allocating combination of chillers and cooling towers can be previously designed depending upon the surrounding features of the site, so as to achieve the optimal power-saving performance of the chiller system. However, for those factories or buildings those have being built, since the numbers and locations of the chillers and the cooling towers are fixed, if the power-saving efficiency is intended to be enhanced through a re-designing process, the building must be reconstructed, and the factories or buildings cannot be used temporarily. Therefore, a preferred method is to change the operating setting of the chiller system to ensure that the chiller system can achieve the expected chilling effect with the lowest power consumption.
The changing the operating setting of the chiller system is mainly categorized into two types. One is to monitor temperatures at specific positions in the chiller system, so as to adjust the operating setting of the chiller system by the change of the temperature of these specific positions, so as to achieve the lowest power consumption. However, through this way, the temperatures at the specific positions are retrieved as system feedback parameters, and a single control parameter is used to adjust the specific subsystem, the operating setting of the subsystem must be switched frequently, and the power-saving benefit is still limited. The other one is to evaluate the chiller system at the first place, and then, the optimal operating setting is obtained to operate the chiller system. For example, in U.S. Pat. Nos. 5,040,377, 5,600,960, 6,047,555, and 6,446,448, after the load of the specific subsystem in the chiller system has been evaluated, a corresponding control parameter is obtained to control the load of the subsystem, such that the power consumption of the subsystem is controlled at the optimal state, which does not excessively output. However, only the specific subsystem is evaluated and adjusted, and other subsystems may overload or excessively output, such that the operation of other subsystems causes additionally unnecessary power consumption, and thus, the practical power-saving benefit is reduced.